Why Sympathize?

In the novel The House of Sand and Fog by Andrew Dubus III, he creates a main character named Kathy.  In the story, she comes into conflict with another character.  The conflict stems from a house.  The house had originally been her fathers, and before foreclosure, was her own.  The foreclosure  occurred after she failed to recognize the letters coming constantly as warnings that this would happen.  The excuse given to her by the author is that she is a recovering drug-addict that is more focused on the recovery.  This excuse is created in order to grab the readers attention and to make them feel sympathy towards her.  

Kathy should not be sympathized!  The fact that she is in a state of rehabilitation is no excuse for not following up on her everyday life.  Had she just taken the time, and not been lazy, to open the letters she would have known the whole time that this process was occurring.  If anything, the fact that she is recovering should mean that she is taking more time to focus on her everyday life in order to keep her mind off of the addiction at hand.  When beginning a habit as such, one has their own choice and should never expect to use it as an excuse.  Though addictions are life-changing, the government is not exactly understanding towards the effects of something already illegal. 

As well as the drugs, Kathy takes advantage of someone who shows he cares about her, Lester.  She uses him to try to get the house back, even though she is well aware that his entire life could be ruined by what she wants him to do.  If she can't feel sympathy to those she is blatantly hurting, then why does he deserve sympathy from the reader?  It is just as the childhood "golden rule" says:  "Treat others the way you would like to be treated."